• Smart Structures and Systems
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• v.10 no.4_5
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• pp.375-391
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• 2012

This paper reports the structural health monitoring benchmark study results for the Canton Tower using Bayesian methods. In this study, output-only modal identification and finite element model updating are considered using a given set of structural acceleration measurements and the corresponding ambient conditions of 24 hours. In the first stage, the Bayesian spectral density approach is used for output-only modal identification with the acceleration time histories as the excitation to the tower is unknown. The modal parameters and the associated uncertainty can be estimated through Bayesian inference. Uncertainty quantification is important for determination of statistically significant change of the modal parameters and for weighting assignment in the subsequent stage of model updating. In the second stage, a Bayesian model updating approach is utilized to update the finite element model of the tower. The uncertain stiffness parameters can be obtained by minimizing an objective function that is a weighted sum of the square of the differences (residuals) between the identified modal parameters and the corresponding values of the model. The weightings distinguish the contribution of different residuals with different uncertain levels. They are obtained using the Bayesian spectral density approach in the first stage. Again, uncertainty of the stiffness parameters can be quantified with Bayesian inference. Finally, this Bayesian framework is applied to the 24-hour field measurements to investigate the variation of the modal and stiffness parameters under changing ambient conditions. Results show that the Bayesian framework successfully achieves the goal of the first task of this benchmark study.

• Korean Journal of Environment and Ecology
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• v.25 no.3
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• pp.389-403
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• 2011

Studies on effects of human action on the destruction of ecosystems and changes in biodiversity are being processed actively from the view point of landscape ecology. This study investigated present distribution status of the naturalization plant by disturbance of natural ecosystem which could be seen on 35 rural villages in Korea. The study made a landuse map on the study area then quantified the landscape ecologic characteristic using landscape index based on this landuse map. Correlation between landscape index on the study area and distribution characteristic of naturalization plant was analyzed. The landscape index was calculated by FRAGSTATS, a spatial analysis program, and naturalization index and urbanization index were used in the distribution characteristic of naturalization plant. As a result, naturalization index and patch density, naturalization index and edge density, naturalization index and area-weighted mean shape index were shown as having positive correlation, and naturalization and core area percentage of landscape, naturalization index and mean core area were displayed as having negative correlation.

• Journal of Korean Biological Nursing Science
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• v.22 no.1
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• pp.11-22
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• 2020

Purpose: The purpose of this study was to evaluate the effect of aerobic exercise on serum lipids, body weight, and body mass index in adults with hypertension using a systematic review and meta-analysis. Methods: Six electronic databases (PubMed, EMBASE, Co-chrane library, CINAHL, PsycINFO, SPORTDiscus) and five domestic databases were searched for randomized controlled trials studies. We used random effect models to derive weighted mean differences (WMD) and their 95% confidence intervals (CI) of aerobic exercise on serum lipids, body weight, and body mass index. Results: Nineteen studies met our inclusion criteria. In comparison with the control group, triglyceride level (TG) (-13.49 mg/dL, 95% CI: -26.74 to -0.24) and body weight (-0.62 kg, 95% CI: -1.08 to -0.16) difference between follow-up and baseline was significantly reduced in the aerobic exercise group. However, no difference was found in total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C) and body mass index (BMI). Conclusion: Aerobic exercise is effective in reducing the TG level and body weight in adults with hypertension. In order to improve levels of serum TC, LDL-C and HDL-C of hypertensive patients, it's needed to combine other intervention methods such as diet therapy.

• Speech Sciences
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• v.5 no.1
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• pp.7-21
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• 1999

This paper proposes an improved training procedure in speech recognition based on the continuous density of the Hidden Markov Model (CDHMM). Of the three parameters (initial state distribution probability, state transition probability, output probability density function (p.d.f.) of state) governing the CDHMM model, we focus on the third parameter and propose an efficient algorithm that determines the p.d.f. of each state. It is known that the resulting CDHMM model converges to a local maximum point of parameter estimation via the iterative Expectation Maximization procedure. Specifically, we propose two independent algorithms that can be embedded in the segmental K -means training procedure by replacing relevant key steps; the adaptation of the number of mixture Gaussian p.d.f. and the initialization using the CDHMM parameters previously estimated. The proposed adaptation algorithm searches for the optimal number of mixture Gaussian humps to ensure that the p.d.f. is consistently re-estimated, enabling the model to converge toward the global maximum point. By applying an appropriate threshold value, which measures the amount of collective changes of weighted variances, the optimized number of mixture Gaussian branch is determined. The initialization algorithm essentially exploits the CDHMM parameters previously estimated and uses them as the basis for the current initial segmentation subroutine. It captures the trend of previous training history whereas the uniform segmentation decimates it. The recognition performance of the proposed adaptation procedures along with the suggested initialization is verified to be always better than that of existing training procedure using fixed number of mixture Gaussian p.d.f.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.9
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• pp.2167-2172
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• 2015

Due to the recent progress in information technology, demand for video imaging devices such as displays has grown. In general, images experience deterioration during the process of transmission due to various reasons. Many studies have boon undertaken on ways o reduce such noise. This paper6 suggests an algorithm that makes a judgment on the noise in order to remove the salt & pepper noise and replaces original pixels if they are non-noise while processing noise according to its density. The suggested algorithm shows a high PSNR of 30.49[dB] for Goldhill images that had been damaged of a high density salt & pepper noise(P = 60%), Compared to the exising CWMF, SWMF, and A-TMF, there were improvements by 17.74[dB], 11.52[dB], and 13.76[dB], respectively.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.2
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• pp.475-481
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• 2014

As the society develops to advanced digital information times, many studies are underway about digital video processing technology areas such as image restoration. There are typical methods to restore the image which have been damaged by the impulse noise like SM(standard median) filter and CWM(center weighted median) filter. These filters show excellent noise reduction capabilities in low noise density areas, but in high noise density areas, noise reduction capabilities are not sufficient. In this paper, in order to restore the degraded images in impulse(Salt & Pepper) noise environment, the image restoration filter algorithm was suggested which expands and subdivide the mask focusing on damaged pixels. And to demonstrate the superiority of the proposed algorithm used PSNR (peak signal to noise ratio) as the standard of judgement.

• Journal of Korean Neurosurgical Society
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• v.66 no.4
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• pp.418-425
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• 2023

Objective : Deciphering the anatomy of posterior communicating artery (PCoA) aneurysms in relation to surrounding structures is essential to determine adjuvant surgical procedures. However, it is difficult to predict surgical structures through preoperative imaging studies. We aimed to present anatomical structures using preoperative high-resolution three-dimensional proton density-weighted turbo spin-echo magnetic resonance (PDMR) imaging with simple classification. Methods : From January 2020 to April 2022, 30 patients underwent PDMR before microsurgical clipping for unruptured PCoA aneurysms in a single tertiary institute. We retrospectively reviewed the radiographic images and operative data of these patients. The structural relationship described by PDMR and intraoperative findings were compared. Subsequently, we classified aneurysms into two groups and analyzed the rate of adjuvant surgical procedures and contact with the surrounding structures. Results : Correlations between preoperative PDMR predictions and actual intraoperative findings for PCoA aneurysm contact to the oculomotor nerve, temporal uncus, and anterior petroclinoid fold (APCF) reported a diagnostic accuracy of 0.90, 0.87, and 0.90, respectively. In 12 patients (40.0%), an aneurysm dome was located on the plane of the oculomotor triangle and was classified as the infratentorial type. Compared to the supratentorial type PCoA aneurysm, adjuvant procedures were required more frequently (66.7% vs. 22.2%, p=0.024) for infratentorial type PCoA aneurysm clipping. Conclusion : Preoperative PCoA aneurysm categorization using PDMR can be helpful for predicting surgical complexity and planning of microsurgical clipping.

• Journal of the Korean Association of Geographic Information Studies
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• v.14 no.3
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• pp.110-125
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• 2011

A number of the Bronze Age dwelling sites have been found and excavated in the Yoodoocheon, Onyangcheon and Baekseokdong basins. Two basins are located near Asan and Onyan in the Chungnam Province of South Korea. Baekseokdong is located in Cheonan, Chungnam. 207 dwelling sites are concentrated around the area of $1.3km^2$ in the Baekseokdong. 177 dwelling sites are sparse and distributed over the area of $1.3km^2$ in the Yongdoocheon and Onyangcheon basins. Most of the Bronze Age dwelling sites in those areas located on the hill. The hills have similar geomorphological environments except for slight differences in geological faces. This study analyzes geomorphological environments of the high-density residential zone of the Bronze Age in the Yoodoocheon and the Onyangcheon basins, and then compares them with the results in Baekseokdong. Study results show that high-density residential zone consists mainly of specific micro-landforms such as the Crest slope, the Crest flat and the Upper side slope, and southeast-facing aspect. A lot of Gentle slope lands were distributed in terms of terrain slope but it is far from specific geomorphological environments. This is not weighted in specific value. Our results show that the geomorphological characteristic derived from this study is major considerations to develop dwelling sites in the Bronze Age. This can be useful to discover the possible dwelling sites over other Chungnam hill regions.

• Journal of the Korean Institute of Landscape Architecture
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• v.40 no.6
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• pp.140-147
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• 2012

This study was conducted to investigate optimum planting density for apartment complex. The validity of Landscape Architecture Criteria of Korea was checked for it. We compared our field data with Landscape Architecture Criteria. In this step, the tree density of urban forest was regarded as standard. Field study was examined in 3 apartment complexes located in capital area, especially completed during these 10 years. 10 sites in each complex were selected and tree density per unit area were calculated. This field study data was divided standard size and large size which received weight. And, it was compared and analyzed. And crown projected area(CPA) was calculated considering proper growth of low vegetation and sufficient shade. The outcome shows that minimum size of Landscape Architecture Criteria is rational. But, in the case of planting large size tree received weight, tree density was short comparing with the tree density of urban forest and CPA was less than 50%. By the result of field study in 3 apartment complex, the tree density of apartment complex satisfied or exceeded Landscape Architecture Criteria. But, in the case of planting large size tree, tree density and CPA show high density due to addition planting for deficient landscape. Therefore, the revision of the Landscape Architecture Criteria was required such as deletion or minimization of the weighted clause about the large size tree and regulate the limit CPA not less than 50% and not more than 100%.

• Imaging Science in Dentistry
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• v.36 no.1
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• pp.17-24
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• 2006

Purpose : The objective of this study was to investigate the effect of TMJ disc displacement on the TMJ disc configuration and surrounding osseous structure. Materials and Methods : The proton density and 72-weighted MR images of 57 TMJs were retrospectively studied. These TMJs were divided into three groups according to the anterior disc displacement status on MR sagittal images, those were the normal, anterior disc displacement with reduction (ADWR), anterior disc displacement without reduction (ADWOR). The frequency of disc configuration and surrounding bony change, the border status between articular disc and retrodiscal tissue were investigated according to the positional change of articular disc. Results : There were significant statistical differences of chi-square statistics of TMJ disc configurational type between normal and ADWR/ADWOR group, respectively. Surrounding bony change frequently appeared in ADWOR and a statistically significant difference of chi-square statistics of bony change frequency between normal and ADWOR group was observed. Conclusion : These results suggested that the disc configuration and bony change of TMJ are strongly related to TMJ disc displacement.